Coatings prepared from (i) isocyanate prepolymers based on isophorone diisocyanate and polyalkylene ether polyols, and (ii) diprimary aromatic diamines having at least one alkyl substituent with 2 or 3 carbon atoms in an ortho-position to at least one of the amine groups, are known and discussed in U.S. Pat. No. 4,463,126. Although such coatings have excellent physical properties, for many purposes, the pot life (or gel time) of the composition is too short.
The preparation of polyurethane-polyureas using aromatic amines having alkyl groups in the ortho positions to the amine groups and a wide variety of isocyanate prepolymers is also well known. See, U.S. Pat. No. 3,428,610. Although this patent suggests a wide variety of isocyanates which can be used to prepare the prepolymers used therein (including dicyclohexylmethane-4,4'-diisocyanate; note column 3, line 71 through column 4, line 14, and particularly column 4, line 5), the reference only describes the use of hexamethylene diisocyanate (Examples 1-5 and 8-10) and toluene diisocyanate (Examples 6 and 7) in the working examples. Coatings based on hexamethylene diisocyanate prepolymers, while having good physical properties, tend to have pot lives too short for many purposes.